As Turkey continued air and ground attacks on U.S.-backed militias in neighboring Syria, President Trump urged the Turkish president, Recep Tayyip Erdogan, on Wednesday to limit its military operations and avoid civilian casualties, according to a White House statement.

In a phone call, Trump called on Erdogan to focus on the shared goal of fighting Islamic State militants and avoid military operations that could produce a clash between Turkish and U.S. military forces deployed near the border in northern Syria.

The United States and Turkey are both members of the NATO military alliance, but relations between Ankara and Washington have been strained badly over the past year. Trump's call was at least the third time the administration has complained about Turkish attacks, to no apparent effect.

Turkey has ignored U.S. entreaties that it limit its offensive against Kurdish fighters around the northern Syrian city of Afrin and has threatened to expand eastward toward the Kurdish enclave of Manbij, which is patrolled by U.S. troops.

Trump "urged Turkey to deescalate, limit its military actions, and avoid civilian casualties and increases to displaced persons and refugees," the White House statement said. "He urged Turkey to exercise caution and to avoid any actions that might risk conflict between Turkish and American forces."

Turkey claims the militias include Kurdish insurgents and Islamic State militants. The Kurdish militias have been trained and armed by the U.S. military, which says there are no Islamic State fighters in Afrin.

Turkey said Wednesday that it had killed more than 200 militia fighters in the offensive, which began over the weekend, and that at least three Turkish soldiers were killed. Kurdish officials say those numbers are greatly exaggerated.

In the phone call, the White House said that Trump also "expressed concern about destructive and false rhetoric coming from Turkey."

Erdogan and his aides have accused Washington of protecting Fethullah Gülen, an Islamic cleric who they say orchestrated a failed 2016 military coup and is a terrorist. The Justice Department has said there are no grounds to extradite the cleric, who has lived in rural Pennsylvania for nearly two decades.

Trump also complained that several U.S. citizens and local U.S. Embassy employees were among those targeted by a government-led crackdown after the coup attempt, when Turkish authorities arrested or fired tens of thousands of teachers, journalists, judges, human rights activists and others.